Throughout the specification the term “tunnel” shall be taken as including any form of underground passage either natural or man-made with a significant horizontal component which shall be taken as including tunnels, inclines, declines and the like. Also, throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
There are many occasions in underground mining where it is necessary to seal off a mine tunnel in a temporary basis. One reason for doing this is to provide ventilation control, for example where tunnel routes are changed when a new body of ore is opened. In such applications, it is usual to block the tunnel by building a wall from concrete. When the need for blocking the tunnel has passed, it is then necessary to demolish the wall. Both processes are relatively expensive and time consuming to undertake. Another reason for blocking a tunnel is to control emergency situations, for instance a fire in the mine where it is necessary to quickly prevent the distribution of smoke. In such situations it is often necessary block the tunnel very quickly to be effective.
A further need for temporary blocking of a tunnel concerns the filling of a stope void. Underground mining processes are often undertaken by removal of a segment of ore body known as a stope block. A typical stope block might be approximately 100 m in length, 20 m in width and 60 m in height. After mining of one stope block is completed, it is necessary to fill the void created before mining can commence on adjacent ore. In normal operations, the void is filled with one of the following filling means: paste fill, cement aggregate rock fill (CAP) or cement rock fill (CRF). Prior to the filling of a void, it is necessary to seal any tunnels entering the void so that filling material does not travel into and interfere with the tunnel.
Again, the sealing of a tunnel for this purpose has usually been achieved by erecting a barrier concrete wall, which sometimes must be demolished immediately after the void is filled. Of course, a concrete wall is not re-usable, as, once erected, it cannot be moved to another location.